Select the statement that best distinguishes average emf from instantaneous emf.

• A. Average emf depends on the field alone, while instantaneous emf depends only on the area
• B. Instantaneous emf can be defined only when the flux is constant in time
• C. Average emf is always larger than instantaneous emf for the same process
• D. Average emf uses a finite time interval, while instantaneous emf uses the derivative at a specific moment

Answer: (D)